The present technology relates to compositions comprising ultra-low levels of volatile organic compounds (VOCs), including those that can be considered VOC-free.
Asphalt-based compositions are used in a variety of construction and building applications. These applications include coating, sealing, waterproofing, joining, cementing, and repairing components such as roofing, walls, footings, and foundations. Such compositions are often referred to as adhesives, cements, mastics, caulking, sealants, primers and coatings.
Asphalt-based compositions are also useful for roofing and waterproofing applications, including the construction or repair of built-up roofs, as saturants used with asphalt roll-roofing, for sealing parapet walls and roof penetrations, and for repairs to and sealing of flashings and gutters. Asphalt compositions can also be used for repair of asphalt shingles, and filling of cracks and nail holes in shingles.
To be commercially useful, such compositions should be durable, easy to apply in a variety of conditions, and relatively inexpensive. Existing asphalt-based roofing and waterproofing compositions are typically sold in tubs or cans (ranging from one gallon to 55 gallons) and in tubes, and can be applied, for example, by hand, via trowel or with a caulk gun dispenser.
There are other specialty applications for asphalt-based compositions, including, for example, joint and crack fillers, waterproofing and damp-proofing applications, and tank and pipeline coatings. Compositions designed for such applications typically have their own set of requirements, and are manufactured to meet different ASTM standards.
Asphalt-based compositions for roofing and waterproofing applications are available in a wide variety of grades, typically for use in different applications, different geographic regions and different temperatures. For built-up roofs, the grade of asphalt is described in ASTM D312 according to the material softening point. Specifically, a Type I roofing asphalt has a low softening point and is considered a soft composition. A Type IV roofing asphalt has a high softening point and is considered a hard composition. These, and intermediate grade compositions, are based on the susceptibility of the asphalt to flow at stated roof temperatures and slopes.
Asphalt-based compositions for roofing and other applications include a solvent to keep the composition soft and pliable, so that it can be readily applied. Once applied, the solvent evaporates, leaving residual asphalt and other ingredients in the compositions. Although the solvents vary depending on the manufacturer, grade, and intended application, existing products employ solvents such as naphtha, kerosene, gasoline, and diesel fuel. These compounds are known as volatile organic compounds (VOCs), which contain carbon and evaporate (become a vapor) or “off-gas” at room temperature. Additional VOC solvents include benzene, xylene, methylene chloride, hexane, toluene, trichloroethane, styrene, heptane, methyl-ethyl ketone, butyl acetate and perchloroethylene. One prevalent VOC composition is known as “mineral spirits” and includes those available under the trade name Varsol™ from ExxonMobil.
For example, EP1811004 to Kelly et al. discloses asphalt-based compositions comprising asphalt, solvent, clay, and a propoxylated alcohol-based ether amine salt surfactant. The disclosed compositions utilize solvents that contain significant amounts of VOCs.
U.S. Pat. No. 7,238,230 to Moss et al. discloses asbestos-free compositions intended for use in roof construction and repair, pavement construction and repair, or as a protective coating for building surfaces. The compositions contain asphalt, clay, a propoxylated alcohol-based ether amine salt surfactant, and solvents that contain significant amounts of VOCs.
U.S. Pat. No. 5,730,791 to Krogh et al. discloses asbestos-free compositions comprising asphalt, solvent, clay, and a hindered acid/amine salt surfactant. The surfactant comprises an acid constituent that has at least two alkyl groups bonded to an alpha carbon and an amine constituent comprising a variety of primary, secondary and tertiary amines. Again, the solvents in the disclosed compositions contain significant amounts of VOCs.
U.S. Pat. No. 8,287,635 to Day et al. discusses asphalt compositions for use in road repair applications. Road repair applications are different from building applications in that the road repair material must be capable of filling large voids in pavement, must form a hard, solidified mass in the void, and must remain stable when subjected to roadway traffic and vehicle loads. Consequently, road repair compositions contain a significant percentage of aggregate. For example, the Examples in the '635 patent comprise more than 50% aggregate−36.5% coarse virgin aggregate, 18% fine virgin aggregate, and 40% reclaimed asphalt pavement (“RAP”) that has been graded to coarse aggregate. Generally, road repair compositions, such as the '635 patent compositions, are not acceptable for building applications such as roofing cement, coatings, and water-proofing because they are too heavy and non-uniform. The '635 patent compositions cannot be applied by hand to a building surface with, for example, a trowel or caulk gun. Unlike road patch compositions, for building applications, one desires a material that is pliable enough to produce a smooth surface, that can adhere to vertical surfaces (such as parapet walls and foundations), a material that can seal small cracks and gaps around roof penetrations to prevent water infiltration, and a material that stays pliable over a long period of time under varying weather conditions.
In recent years, there has been widespread concern associated with the use of VOCs, which can cause environmental damage and impact human health. Accordingly, governmental agencies and environmental organizations have sought to limit their use. New regulations have limited the use of VOC containing, solvent-based products.
In response to concerns and regulations governing the use of VOCs, some manufacturers have introduced asphalt-based compositions that employ emulsion technology. Such technology generally involves the use of an emulsifier, which suspends asphalt particles in water or water and oil. Following application, the liquid evaporates leaving the resulting asphaltic composition. Unfortunately, use of water has certain drawbacks and limitations, including that the compositions are susceptible to freezing during storage or in use, resulting in separation of the ingredients and failure of the composition.
Thus, an ongoing need exists for improved compositions that can be described as “ultra-low VOC” that do not employ emulsion-technology. Specifically, there is a need for ultra-low VOC asphalt-based compositions that can provide enhanced performance over known VOC-containing compositions at a reasonable cost; that are environmentally safer than what is currently available; and that are useful for building applications such as roofing applications (including but not limited to roofing and flashing cements, coatings and primers), waterproofing of building foundations and footers, coating of tanks, gutters and pipes; and that can be applied by hand including by trowel or caulk gun; and that exhibit good pliability, workability, flexibility and adhesion, without sagging, slipping or disbanding under a variety of temperatures.